1. Field of the Invention
The present invention concerns a modular filtered electrical connector, more particularly intended for the protection of electronic equipment against excess voltages generated by electromagnetic interference or electrostatic discharges.
2. Brief Description of Related Developments
Protection against these phenomena has formed the subject of numerous studies about the use of filters integrated into the connectors, which are employed both in industrial sites and in instruments carried on board aircraft or of space vehicles.
All solutions studied have nevertheless in common the observance of international standards on the level of complementing a male or female connector, belonging to the same series, a function called the ability to intermarry and that of being able to be interchanged with standard connectors belonging to the same series.
In order to satisfy these two criteria, it has been proposed to use an adapter to convert existing items of equipment, without modifying them.
It is in this way that U.S. Pat. No. 3,961,294 describes the adaptation of a conventional connector by means of a ferrule connected to the back portion of the connector. This electrically conducting ferrule comprises a dividing plate linked to the internal wall of the ferrule and is provided with holes which receive contacts fitted or otherwise with filtration elements. The filtration element housings are soldered to the dividing plate. The ferrule comprises a shoulder, which rests on the flange of the housing, a flange to which it is soldered, thus providing electrical continuity for receiving the ground of the filtration elements. It is evident that such an arrangement necessitates a large amount of space inside the cabinet or the rack, where the connector housing is fixed and makes impossible any replacement of such an adapter as the result of the soldered link.
U.S. Pat. No. 4,729,743 describes a filtered connector, which satisfies the criteria of the ability to be interchanged, whilst providing the functions of filtration and suppression of transients. The components are grouped in a single insert introduced into the central cavity of the connector housing and a ground contact is connected to the housing by soldering or using a conducting epoxy resin. The insert is finally held in place with an insulating potting between sealing discs.
U.S. Pat. No. 5,236,376 describes an insert, which provides electronic protection to a connector against transients. The insert consists of an assembly of printed circuits carrying the filtration elements and the contacts. The insert is connected to the connector housing, in order to provide electrical continuity between these elements and is held in place, according to one embodiment, by insulators placed in front and behind the insert.
These solutions are not however satisfactory, because they do not make possible either the disassembly or the replacement of the inserts and they moreover tolerate only with great difficulty constraints necessitated by the observance of maximum dimensions imposed by users.
The use of rectangular or circular inserts, which after being inserted into the cavities of a housing or a receptacle connector, are fixed into the cavities by a flange held in place by screws working in conjunction with threaded holes made in the back face of the bottom of the housing or the receptacle connector, is moreover known in the prior art.
Lastly, the current technology of filtered connectors proposes elements fixed in the housing, which compels the user of cabinets or racks to modify his equipment extensively, when he wishes either to improve by increasing the number of functions, or to carry out a retrofit ting of the said equipment, or simply when a maintenance operation necessitates the replacement of a part of the connector.
There is therefore a need to provide housings or standard receptacle connectors thanks to which a user can at the design stage choose a connector, which will make possible the modularity or filtration inserts, which can be replaced or installed during the life of operation of equipment incorporating such a connector.